Diagnostic and therapeutic medical procedures often require the use of a surgical device to evaluate and/or treat internal regions of the body. A common surgical instrument used for such purposes is a catheter, which is typically inserted through an incision or fenestration within the patient's vasculature, or orifice of the patient's body. For example, a catheter may be used to facilitate imaging or treatment of a patient's vasculature, such as, for example, removal of a thrombus or other obstruction or foreign body. However, many catheters are unfit for use in such circumstances because of the extremely delicate nature of some vasculature, particularly neurovasculature.
Typical catheters utilize techniques such as hydraulic removal of a thrombus, rotating cutting blades for calcified plaque, inflatable means for crushing or dragging a thrombus, or a multiplicity of metal structures that either self-expand or can be expanded to dredge a vessel or remove a stone. One catheter design comprises a preshaped distal end portion designed to facilitate removal of an occlusion from the tortuous vasculature, including neurovasculature. During insertion of the catheter, a sheath straightens and provides column strength to the preshaped distal end portion. Once the catheter is at the occlusion, the sheath is removed so the distal end portion of the catheter can return to its preformed shape to facilitate engagement with and removal of the occlusion from the desired coronary artery.
Many catheters of the prior art fail to address a major concern for applications into the neurovasculature; namely, minimizing the crossing profile (i.e., the cross-sectional area) of the devices. In general, these prior art catheters are assembled devices consisting of many components that need to either be welded in place, or otherwise fixedly attached, for example, using collars or other means of assembly, thus resulting in larger crossing profiles.
Some catheters address the issue of crossing profile by using fixed wire assemblies which are not meant to pass through a microcatheter, but rather, to navigate from a large guiding catheter situated well proximal of the obstruction in large vasculature. For example, some devices use an assembly in which the wire ends are managed into a collar. A retractable core wire doubles as a conventional distal tip. This tip allows the device to navigate the vasculature and puncture a thrombus, while the large body of the device encompasses the expander. However, this design does not address the majority of anticipated cerebral vascular cases, in which microcatheter/guidewire combinations are used to create a pathway across the clot for angiographic visualization distal to the clot prior to the procedure.
Another type of catheter anticipates the need for smaller devices to achieve neurovasculature compatibility. Such devices use a helically shaped wire held straight for delivery by the microcatheter. The use of a single wire shaped into a ‘cork-screw’ reduces the profile by eliminating complex assembly steps required by earlier catheters. Typically, it is preferred that microcatheters be flexible at the distal end, which makes it difficult for such devices to hold a pre-shaped wire in a straight configuration. To increase distal end flexibility, such devices utilize a less rigid ‘cork-screw,’ which degrades its ability to extract a clot. These devices are also limited in their ability to prevent the distal migration of particulate during the removal of clot due to the inherently large interstices of the single, helically shaped ‘cork-screw’ wire. These devices also require complete removal from the patient following each pass. This adds considerable procedural time and increases radiation exposure to both the patient and the clinical staff.
Thus there exists a need for a recanalization device suited for effective and efficient removal of thrombi from human neurovasculature and peripheral vasculature. Exemplary embodiments of the present invention feature a flexible distal end tube which is capable of more effectively securing thrombus particulate during removal. Those skilled in the art will recognize numerous advantages of such exemplary embodiments over the prior art, for example, reducing distal migration of thrombus particulate during removal.